Bristlecone pine and carbon dating
“And sure enough,” Brunstein said, “There’s a frost ring.” Recording storms is an insightful quirk of bristlecones, but their most useful contribution may be as evidence of how humans are heating up the atmosphere.In 2004, three climatologists from Penn State, the University of Massachusetts and the University of Arizona published a blockbuster study detailing average temperatures in the northern hemisphere for the past 2,000 years. Late-summer storms hurl hail against the granite slope.The dawn air freezes all but six weeks of the year. But on this lonely ridge, the oldest known tree in the Pikes Peak region, a Rocky Mountain bristlecone pine, has been growing for about 2,050 years.These were frost rings — scars left from years when the freezing weather came too soon and ice formed in the cells, shredding the thin walls.An occasional frost ring isn’t unusual, but the cores from near Pikes Peak held almost 200, which gave La Marche an idea.It probably got its start when a gray, jaylike bird called a Clark’s nutcracker hid seeds filched from a nearby pine into a nook on the ridge, then forgot about the stash.Today, the tree’s location is known to fewer than 10 people, who keep the route hidden to protect the ancient pine.
In 1965, a strong El Niño weather pattern in the Pacific brought cold, wet weather to the Rockies, where a young Brunstein woke up to a “God-awful” September storm that dumped more snow than he had ever seen.About the time Brunstein spotted his old trees, the rings of bristlecones proved that radiocarbon dating — the newest, most sophisticated way to measure an object’s age — was inaccurate by at least 1,000 years. To him, the potential of the old pines seemed almost limitless.The only trick was to translate the trees’ language.Since then, scores of scientists have scrutinized the tiny dowel for insight into everything from ancient explosions to Aztec curses to global climate change. So much of the tree is dead, gray wood that it looks a bit like a rhino wearing a wreath. It might have gone on unnoticed if a 16-year-old kid from Colorado Springs named Craig Brunstein hadn’t spied the old tree in 1968 while hiking high in the mountains.So many have used the pine to study the climate that it has become a sort of global black box — a flight recorder for the past 2,000 years of Earth. Still, like all old bristlecones, it seems to exude an enduring nobility. “I loved everything outdoors, and I was really into trees — identifying them, finding their ages.